Stereochemical Study of Cycloadditions Using Erythrose and Threose Based Dienes as Source of 2-Nonulosonic Acid Analogs

Abstract
The stereochemical outcome of the hetero Diels Alder reaction of an erythrose based diene with sodium glyoxylate was rationalized by preparing the same compounds via decarboxylation of 2-carbethoxy-2-deoxy-2-ulosonic esters, obtained by cycloaddition with diethyl ketomalonate. Further chemical transformations of cycloadducts allowed us to prepare a series of new 2-nonulosonic acid derivatives.